An image data interface between a printer and its server, or digital front end (DFE), which specifies the data to be transferred between an interface card in the printer which is electrically connected to the digital front end and the rendering, halftoning, card in the printer which halftones the image, the interface data including contone image data, printing hints and page and line start signals.
How to optimally connect various computer peripherals to a computer has been a continuing problem. A computer usually has a backplane which provides a standard interface between cards, and a peripheral such as a disk drive may be sold with an interface card that communicates between the drive and the backplane. In this case, the backplane is the interface.
A different configuration is used in a modem networked printer. The generation of a page containing text and image data frequently starts at a terminal where the user generates a computer generated graphic or receives a contone image from a scanner, generates text, combines image and text in a highly compressed form using a page description language (PDL), and sends the result to a printer server, a DFE, which is usually located somewhere near the printer. Here, a decomposer expands the PDL into separations of bit maps and sends the resultant video over wire or fiber cables or a network to the printer. Finally, the printer has an interface card which reformats the data into rasters, halftones them in a rendering card, and applies them to the raster output scanner (ROS). In this case, the interface is the connection between the server and the printer.
The problem with this system is that different server manufacturers build their servers to output over different systems, like wire or fiber, cable or networks, using different data protocols, and this puts a large burden on the printer manufacturer to design the printer to accept the interface restrictions of the server or servers being used.